Solutions manual for database systems design implementation and management 12th edition by coronel All Chapters 1-16

Appendix C The University Lab: cn cn cn cn




Conceptual Design Verification, Logical Design, and Implementation cn cn cn cn cn cn




Appendix C cn




The UniversityLab: ConceptualDesign, Verification, cn cn cn cn cn




Logical Design,and Implementation cn cn cn cn




Discussion Focus cn




How is a database design verified, and why is such verification necessary?
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Use our detailed answer to question 1 to focus class discussion on database design verification. Stress that
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the verification process uses the initial ER model as a communication tool.
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The designer may begin the verification process by describing the organization's operations to its end users,
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basing the detailed description on the initial ER model. Next, explain how the operations will be supported by
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the database design. Stress that the design must support the end-user application views, outputs, and
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inputs. Points to be addressed include such questions as:
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• Is the description accurate? If not, what aspects of the description must be corrected?
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• Does the model support the end-user requirements? If not, what aspects of the end-
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userrequirements have not been addressed or have been addressed inadequately?
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Keep in mind that even a model that perfectly addresses all initially determined end user requirementsis
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likely to need adjustments as those end users begin to understand the ramifications of the database design's
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capabilities. In many cases, the end users may learn what the organization's processes and procedures
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actually are, thus leading to new requirements and the perception of new opportunities. The database
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designer must keep such likely developments in mind, especially if (s)he works as a database design
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consultant. (Anticipation of such developments must be factored into the contract negotiations for
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consulting fees.)
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Discuss the role of the system modules. cn cn cn cn cn cn




1

, Appendix C The University Lab: cn cn cn cn




Conceptual Design Verification, Logical Design, and Implementation cn cn cn cn cn cn




The use of system modules can hardly be overemphasized in a database design environment.
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cStressthese module characteristics and features:
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• Modules represent subsets of the database model: Smaller "pieces" are more easily
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understood.
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• Modules are self-contained and accomplish a specific system function; if such a system
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function must be modified, other functions remain unaffected.
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• Modules fit into a modular database design, which is more easily modified and adapted tonew
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circumstances. Because modification efforts are focused on a database subset, productivity of
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both designers and application developers is likely to be enhanced.
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Module interfaces must be clear if the modules are expected to work well within the overall system.
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2

, Appendix C The University Lab: cn cn cn cn




Conceptual Design Verification, Logical Design, and Implementation cn cn cn cn cn cn




Answers to Review Questions cn cn cn




1. Why must a conceptual model be verified? What steps are involved in the verification process?
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The verification of a conceptual model is crucial to a successful database design. The verification process
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allows the designer to check the accuracy of the database design by:
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• Re-examining data and data transformations. cn cn cn cn




• Enabling the designer to evaluate the design efficiency relative to the end user's and c n c n c n c n c n c n c n c n c n c n c n c n c n




system's design goals.
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Keep in mind that, to a large extent, the best design is the one that serves the end-user requirements
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best. For example, a design that works well for a manufacturing firm may not fit the needs of a marketing
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research firm, and vice versa.
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The verification process helps the designer to avoid implementationproblems later by:
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• Validating the model's entities. (Remember the minimal data rule.) cn cn cn cn cn cn cn cn




• Confirming entity relationships and eliminating duplicate, unnecessary, or improperly cn cn cn cn cn cn cn cn




defined relationships.
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• Eliminating data redundancies. cn cn




• Improving the model's semantic precision to better represent real-world operations. cn cn cn cn cn cn cn cn cn




• Confirming that all user requirements (processing, performance, or security) are met. cn cn cn cn cn cn cn cn cn cn




Verification is a continuous activity in any database design. The database design process is evolutionary
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in nature: It requires the continuous evaluation of the developing model by examining the effect of
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adding new entities and by confirming that any design changes enhance the model's accuracy.
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The verification process requires the following steps:
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1. Identify the database's central entity. cn cn cn cn




The central entity is the most important entity in our database, and most of
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cthe otherentities depend on it.
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3

, Appendix C The University Lab: cn cn cn cn




Conceptual Design Verification, Logical Design, and Implementation
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2. Identify and define each module and its components.
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The designer divides the database model into smaller sets that reflect the data
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cneeds ofparticular systems modules such as inventory, orders, payroll, etc.
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3. Identify and define each of the module's processes.
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Specifically, this step requires the identification and definition of the database transactions
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that represent the module's real-world operations.
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